Municipal water contains a disinfectant, typically chlorine or chloramine, to prevent the growth of harmful pathogens as it travels to your home. While these compounds ensure the water is safe for consumption, they can impart an unpleasant taste or odor. They also pose a threat to sensitive applications like aquatic environments and certain plants. The time required to eliminate these disinfectants varies depending on the specific compound used and the removal method chosen.
Dechlorination Through Natural Evaporation
The simplest approach to removing the disinfectant is natural dissipation, often called off-gassing. This method is effective only for free chlorine, a highly volatile chemical that readily converts from a dissolved state in water to a gas. The time required depends on environmental factors like temperature, air circulation, and the water’s surface area.
At room temperature in an open container, free chlorine levels can significantly decrease within 12 to 24 hours, though complete removal may take up to five days. Increasing the water temperature speeds up molecular movement, accelerating the conversion of chlorine from liquid to gas.
Chloramine is a more stable disinfectant, formed by bonding chlorine with ammonia, which utilities use to maintain a longer-lasting residual in the pipes. Due to this chemical stability, chloramine does not readily off-gas like free chlorine. Letting water sit for days or boiling it will not rapidly remove chloramine, necessitating a different strategy.
Accelerating the Process Using Physical Methods
Physical agitation and heat can significantly shorten the time needed to remove free chlorine from water. Aeration speeds up the gas exchange between the water and the air, promoting the faster release of volatile chlorine gas. This can be done by pouring the water between two buckets or by using an aquarium air stone and pump to bubble air through the water.
Vigorous aeration can reduce free chlorine levels in minutes to a few hours, depending on the water volume. Applying heat is also effective, as chlorine volatility increases at higher temperatures. Bringing water to a rolling boil and maintaining it for 15 to 20 minutes can virtually eliminate free chlorine content.
These physical methods are not reliable solutions for chloramine, as the strong chemical bond resists evaporation, aeration, and boiling. For water treated with chloramine, or when time is critical, chemical intervention is necessary.
Chemical Neutralization for Instant Dechlorination
The most rapid and reliable method for removing both chlorine and chloramine involves chemical neutralization. This process uses a reducing agent that instantly reacts with the disinfectant compounds, rendering them harmless. Common chemical dechlorinators contain compounds like sodium thiosulfate or ascorbic acid, available in liquid or tablet form.
These neutralizers instantly convert chlorine and chloramine into harmless chloride ions, which are naturally present in water. The chemical reaction is nearly instantaneous, meaning the water is dechlorinated within seconds of adding the proper dose. This speed makes chemical neutralization the preferred method for treating large volumes or highly sensitive applications.
Dosing is based on the water volume and disinfectant concentration, requiring careful adherence to product instructions for complete neutralization. Since this method works equally well on both free chlorine and chloramine, it removes uncertainty about the utility’s disinfectant choice.
Practical Applications and Water Sensitivity
Quick dechlorination is necessary in environments where the disinfectant is toxic to living organisms. Aquatic life, such as fish and amphibians, are highly sensitive because the compounds readily pass through their gills into the bloodstream. Introducing untreated tap water can cause immediate respiratory distress and fatal poisoning.
Chlorine and chloramine can also destroy the beneficial bacteria colonies established in aquarium biological filters. These microbes break down toxic fish waste, and their sudden elimination can lead to a tank environment crash. Therefore, water for aquariums must be instantly treated with a chemical neutralizer before use.
Plants and gardening are also sensitive, as disinfectants can harm the beneficial soil microbes that support plant health. While most plants tolerate low tap water levels, sensitive species or hydroponic systems require treatment to protect roots and symbiotic microorganisms. A simple testing kit can confirm that the chlorine or chloramine level has reached zero parts per million, ensuring the water is safe for its intended use.